1. Field of the Invention
The present invention relates to a fixing device that heats and fixes, onto a recording material, a toner image formed on the recording material and to an image forming apparatus that uses an electrophotography recording technique, such as a copying machine or a printer including the fixing device.
2. Description of the Related Art
Electrophotographic image forming apparatuses include a fixing device that fixes a toner image formed on a recording material. Generally, a contact-type fixing device including a roller or a belt is used, and a toner image is heated and fixed by bringing the roller or the belt into contact with the toner image.
With such contact-type fixing device, a phenomenon called toner offset is inevitably caused. Toner offset is a phenomenon where part of a toner image on a recording material adheres to the roller or the belt and the part of the toner image is removed from the recording material as a result. In one method for preventing such toner offset, toner containing a wax component made of a hydrocarbon compound is used.
If such toner including wax is used, the wax is liquefied by heating performed when the toner image is fixed. Part of the liquefied wax could be vaporized. The vaporized component is solidified immediately after vaporization and floats inside the device. If the temperature inside the device rises as the device operates, the floating component (hereinafter referred to as wax component) is liquefied and adheres to various parts inside the device. If the wax component adheres to a conveyance guide, the wax component hinders movement of a recording material. If the wax component adheres to a conveyance roller, the friction coefficient of the roller is decreased. In either case, performance in conveying a recording material is decreased. In addition, a recording material could be jammed by these phenomena.
Recently, there has been a growing demand for image forming apparatuses that operate at a higher speed. Forming images at a higher speed while satisfying fixability of toner requires more energy than ever. Thus, it is necessary to ensure energy given to a toner image on a recording material, for example, by increasing the width of the fixing nip portion in the fixing device or by increasing the control temperature of the fixing device. However, as a result of such increase, the amount of the component vaporized from the wax is increased, and various problems are easily caused by the above adhesion of the wax component.
Japanese Patent Application Laid-Open No. 2010-249874 discusses arranging a capture member for capturing the wax component on the inside of a frame of a fixing device.
To capture the wax component, it is desirable that the temperature of the capture member be set so that the wax component remains in a liquid state. If the temperature of the capture member is too low, since the floating wax component is solid substance, the wax component is slid on the capture member. Namely, the wax component is not adsorbed on the capture member. If the temperature of the capture member is too high, the wax component adsorbed on the capture member is vaporized again. Thus, to effectively capture the vaporized component, it is important to maintain the temperature of the capture member within an appropriate temperature range. A device capable of setting the temperature of the capture member at a more appropriate temperature than the device discussed in Japanese Patent Application Laid-Open No. 2010-249874 is demanded.